1. Field of the Invention
The present invention relates to dust removal for use in mining and other dusty workplace environments, and especially to dust suppression arrangements for use in conjunction with a mining shearer device to suppress dust generated.
2. Description of Related Art
Respirable dust is a health hazard to those working in the dusty environment, is a cause of respiratory complaints, and presents other dangers by limiting visibility by the workers. Because of this, workplace rules specify maximum permissible dust concentrations and/or exposures.
One activity which generates a considerable amount of dust in a confined space is mining, one form of which is the long wall mining technique often used for coal extraction.
Long wall mining involves the driving of a pair of parallel gate roads, referred to as the maingate and the tailgate, in the plane of the mineral ore seam, the gate roads being spaced apart by a distance referred to as the long wall. A mining machine, known as a shearer, then mines the coal face in the long wall by cutting the long wall in a direction transverse to the gate roads. The coal is extracted placed on an armoured conveyor and then conveyed to the maingate, fed into a crusher and then deposited on a rubber conveyor belt which carries the coal out of the mine. Support and drive means for the mining machine can be mounted in the gate roads.
The shearer machine has a shearer body which extends generally parallel to the long wall coal face, with a pivot joint at one end to a shearer arm supporting the shearer drum which performs the cutting. The drum is generally cylindrical and is driven to rotate about its axis, which is perpendicular to the face.
The position of the drum on the coal face is swept up and down by pivoting of the shearer arm relative to the shearer body, while horizontal movement across the long wall face is performed by movement of the shearer body.
Respirable dust may be produced by the cutting operation or as the long wall shearer machine moves forward or by associated operations in the mine. Ventilation is provided to maintain an air flow along the long wall to help reduce dust problems, but this is often insufficient on its own to meet appropriate standards and further measures are required.
U.S. Pat. No. 4,251,567 discloses a cowl-like dust scrubber fitted to the shearer drum at its trailing side to capture dust generated by the cutting operation, incorporated into or attached to the cowl which usually resides at that location.